1. Field of the Invention
The present invention relates to a novel production process of hydantoin derivatives, which are useful as intermediates for the production of pharmaceutical chemicals such as .alpha.-keto carboxylic acids and amino acids including phenylalanine.
2. Description of the Related Art
Typically, 5-substituted hydantoins are produced by a so-called Wheeler-Hoffman process (see J. Am. Chem, Soc., 45, 369 (1911)). According to this process, carbonyl compounds, especially aldehydes and hydantoins are condensated in the presence of acetic acid and anhydrous sodium acetate. Furthermore, this reaction can be carried out in the presence of anhydrous piperazine (see Org. Syn., Coll. Vol. 5, 627).
These processes are, however, disadvantageous from the industrial point of view in that expensive organic solvents must be used in the reaction and the yield of the desired hydantoin derivatives is as low as approximately 70%.